In general, it is known that about 54% of carbon dioxide generated in the industry is discharged in thermal power plants. Because carbon dioxide is a gas that is generally generated in the process of burning fuels, the amount of discharged carbon dioxide should be reduced at a fuel combustion time point.
The existing thermal power plants use an air combustion method in which air is used as an oxidizer and burns fossil fuels such as coal, petroleum, and natural gases are burned to produce electric power. The air combustion method uses only oxygen that occupies about 21% of air as a pure oxidizer, and nitrogen that occupies about 79% of air is unnecessarily heated.
Meanwhile, because a considerable amount of calories generated when air is burned is used to heat nitrogen, heat loss is caused, and because the concentration of carbon dioxide in the flue gas is as low as 20% or less, considerable costs are consumed to concentrate dioxide of low concentration in the flue gas to a high concentration.
Accordingly, in recent years, a pure oxygen combustion method for burning fuels by using only oxygen instead of air as an oxidizer has been developed. Unlike the existing air combustion method, the pure oxygen combustion method reduces the heat loss of the burned gases by about 75% to 80% as it rarely burns nitrogen components, and the main component of the flue gas consists of carbon dioxide (CO2) and moisture (H2O).
If oxygen is used as an oxidizer, it is difficult to adjust flames because a rapid exothermic reaction is caused when the oxidizer makes contact with a fuel as compared with the case in which air is used as an oxidizer. That is, in general, while the pure oxygen direction combustion has a good thermal efficiency and discharges a small amount of atmospheric contaminants, it produces combustion gases of high temperature of 3000 degrees or higher so that it is difficult to apply the method to a heat exchanger.
In order to solve the above-mentioned problems, Korean Patent Application Publication Nos. 10-2012-0033458 and 10-2011-0010731 relate to a measure for producing electric power by using a pure oxygen combustion boiler system, and disclose inventions related to an improved measurement for improving a thermal efficiency and an energy reducing effect through a process of exchanging heat between flue gases of high temperature, high temperature steam, and condensation heat generated in a power generation process through pure oxygen combustion and a part of the interior of a power oxygen combustion generation apparatus that is to be heated, or minimizing loss of electric power produced by a dual ignition boiler.
However, the cited documents disclose only that parts of waste steam or flue gases discharged from a combustion unit are heat exchanged and supply water is preheated and vapor is reheated for heat exchange through recirculation of combustion gases, and fail to disclose a pure oxygen direct combustion apparatus that does not accompany recirculation of combustion gases.
In order to solve the above-mentioned problems, the present invention provides a pure oxygen direct combustion system using a liquid metal in which sensible heat of high temperature generated in a pure oxygen combustion reaction process of a solid fuel is provided to a metal in the reactor to be used in a metal liquefying process and is circulated and supplied and heat is exchanged in a process of circulating a liquid metal of high temperature so that an overload of the reactor can be reduced in the process of supplying the liquid metal of a middle/low temperature into the reactor again.